Method and apparatus for performing communication in wireless power transmission system

ABSTRACT

The present invention is related to an apparatus and method for performing communication in a wireless power transfer system. The description discloses a wireless power transmitter including a communication/control unit configured to perform a negotiation for a first available power indicator with a wireless power reception apparatus; and a power conversion unit configured to transmit a wireless power to the wireless power reception apparatus by generating magnetic coupling in a primary coil according to the first available power indicator. The wireless power transmitter provides an effect that a wireless power transmission apparatus is available to obtain status and authority as a master/transmitter depending on a situation, and current ambient situation/environment is reflected in real time.

CROSS REFERENCE TO RELATED APPLICATION

This non-provisional application claims the benefit under 35 U.S.C. §119(a) to Patent Application No. 10-2018-0034709, filed in the Republicof Korea on Mar. 26, 2018, all of which is hereby expressly incorporatedby reference into the present application.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless power transmission, and moreparticularly, to a method and apparatus for performing communication ina wireless power transmission system.

Related Art

The wireless power transfer (or transmission) technology corresponds toa technology that can wirelessly transfer (or transmit) power between apower source and an electronic device. For example, by allowing thebattery of a wireless device, such as a smartphone or a tablet PC, andso on, to be recharged by simply loading the wireless device on awireless charging pad, the wireless power transfer technique may providemore outstanding mobility, convenience, and safety as compared to theconventional wired charging environment, which uses a wired chargingconnector. Apart from the wireless charging of wireless devices, thewireless power transfer technique is raising attention as a replacementfor the conventional wired power transfer environment in diverse fields,such as electric vehicles, Bluetooth earphones, 3D glasses, diversewearable devices, household (or home) electric appliances, furniture,underground facilities, buildings, medical equipment, robots, leisure,and so on.

The wireless power transfer (or transmission) method is also referred toas a contactless power transfer method, or a no point of contact powertransfer method, or a wireless charging method. A wireless powertransmission system may be configured of a wireless power transmittersupplying electric energy by using a wireless power transfer method, anda wireless power receiver receiving the electric energy being suppliedby the wireless power transmitter and supplying the receiving electricenergy to a receiver, such as a battery cell, and so on.

The wireless power transfer technique includes diverse methods, such asa method of transferring power by using magnetic coupling, a method oftransferring power by using radio frequency (RF), a method oftransferring power by using microwaves, and a method of transferringpower by using ultrasound (or ultrasonic waves). The method that isbased on magnetic coupling is categorized as a magnetic induction methodand a magnetic resonance method. The magnetic induction methodcorresponds to a method transmitting power by using electric currentsthat are induced to the coil of the receiver by a magnetic field, whichis generated from a coil battery cell of the transmitter, in accordancewith an electromagnetic coupling between a transmitting coil and areceiving coil. The magnetic resonance method is similar to the magneticinduction method in that is uses a magnetic field. However, the magneticresonance method is different from the magnetic induction method in thatenergy is transmitted due to a concentration of magnetic fields on botha transmitting end and a receiving end, which is caused by the generatedresonance.

In a communication protocol between a wireless power transmissionapparatus and a reception apparatus, in the case that a sender or amaster that initiates or leads a communication is the receptionapparatus, the wireless power transmission apparatus may transmit only aresponse to a request of the wireless power reception apparatus. In thiscase, even in the case that the wireless power transmission apparatusdetects foreign substances in a charging area (or magnetic field area)or charging environment is changed, the wireless power transmissionapparatus is unable to adjust a power level actively on a desired timingand unable to perform an authentication.

Accordingly, a method and apparatus for performing efficient and safepower management and authentication is required such that a wirelesspower transmission apparatus is available to obtain status and authorityas a master/transmitter depending on a situation, and current ambientsituation/environment is reflected in real time.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for performing acommunication in a wireless power transmission system.

The present invention also provides a method and wireless powertransmission apparatus for performing a communication in a wirelesspower transmission system.

The present invention also provides a method and wireless powerreception apparatus for performing a communication in a wireless powertransmission system.

According to an aspect of the present invention, a wireless powertransmission apparatus is provided. The apparatus includes acommunication/control unit configured to perform a negotiation for afirst available power indicator with a wireless power receptionapparatus and a power conversion unit configured to transmit a wirelesspower to the wireless power reception apparatus by generating magneticcoupling in a primary coil according to the first available powerindicator. Here, the communication/control unit is configured to:receive a received power packet indicating a power received by thewireless power reception apparatus from the wireless power receptionapparatus, transmit a bit pattern response requesting a communication bythe wireless power transmission apparatus to the wireless powerreception apparatus, receive a response signal indicating being ready toreceive the communication by the wireless power transmission apparatusfrom the wireless power reception apparatus, and transmit a packetrelated to a second available power indicator to the wireless powerreception apparatus.

In an aspect, the first available power indicator and the secondavailable power indicator may be guaranteed power.

In another aspect, the first available power indicator and the secondavailable power indicator may be target power.

In still another aspect, the packet related to the second availablepower may include a capability packet of the wireless power transmissionapparatus.

In still another aspect, the bit pattern response may indicate torequest an authority acquisition that the wireless power transmissionapparatus is available to transmit a predetermined packet to thewireless power reception apparatus.

In still another aspect, the bit pattern response is defined with adifferent pattern from a bit pattern for ACK response, NAK response andND response indicating the request is not valid.

According to another aspect of the present invention, a wireless powertransmission method is provided. The method includes performing anegotiation for a first available power indicator with a wireless powerreception apparatus, transmitting a wireless power to the wireless powerreception apparatus by generating magnetic coupling in a primary coilaccording to the first available power indicator, receiving a receivedpower packet indicating a power received by the wireless power receptionapparatus from the wireless power reception apparatus, transmitting abit pattern response requesting a communication by the wireless powertransmission apparatus to the wireless power reception apparatus,receiving a response signal indicating being ready to receive thecommunication by the wireless power transmission apparatus from thewireless power reception apparatus, and transmitting a packet related toa second available power indicator to the wireless power receptionapparatus.

According to still another aspect of the present invention, a wirelesspower reception apparatus is provided. The apparatus includes acommunication/control unit configured to perform a negotiation for afirst available power indicator with a wireless power transmissionapparatus and a power pickup unit configured to receive a wireless powerfrom the wireless power transmission apparatus through magnetic couplinggenerated in a primary coil according to the first available powerindicator. Here, the communication/control unit is configured to:transmit a received power packet related to the received wireless powerto the wireless power transmission apparatus, receive a bit patternresponse requesting a communication by the wireless power transmissionapparatus from the wireless power transmission apparatus, transmit aresponse signal indicating being ready to perform the communication bythe wireless power transmission apparatus to the wireless powertransmission apparatus, and receive a packet related to a secondavailable power indicator from the wireless power transmissionapparatus.

According to still another aspect of the present invention, a wirelesspower reception method is provided. The method includes performing anegotiation for a first available power indicator with a wireless powertransmission apparatus, receiving a wireless power from the wirelesspower transmission apparatus through magnetic coupling generated in aprimary coil according to the first available power indicator,transmitting a received power packet related to the received wirelesspower to the wireless power transmission apparatus, receiving a bitpattern response requesting a communication by the wireless powertransmission apparatus from the wireless power transmission apparatus,transmitting a response signal indicating being ready to perform thecommunication by the wireless power transmission apparatus to thewireless power transmission apparatus, and receiving a packet related toa second available power indicator from the wireless power transmissionapparatus.

According to the present invention, there is an effect that a wirelesspower transmission apparatus can adjust an available power indicatordynamically on a desired timing depending on ambientenvironment/situation and initiate a communication and an authenticationautonomously.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless power system (10) according toan exemplary embodiment of the present invention.

FIG. 2 is a block diagram of a wireless power system (10) according toanother exemplary embodiment of the present invention.

FIG. 3 shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transmission system.

FIG. 4 is a block diagram of a wireless power transmission systemaccording to another exemplary embodiment of the present invention.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

FIG. 6 shows a power control method according to an exemplary embodimentof the present invention.

FIG. 7 is a block diagram of a wireless power transmitter according toanother exemplary embodiment of the present invention.

FIG. 8 shows a wireless power receiver according to another exemplaryembodiment of the present invention.

FIG. 9 shows a communication frame structure according to an exemplaryembodiment of the present invention.

FIG. 10 is a structure of a sync pattern according to an exemplaryembodiment of the present invention.

FIG. 11 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an exemplaryembodiment of the present invention.

FIG. 12 illustrates an available power indicator according to anexample.

FIG. 13 illustrates a method of each available power indicator being setin a negotiation phase according to an example.

FIG. 14 illustrates a method of each available power indicator being setin a negotiation phase according to another example.

FIG. 15 is a diagram illustrating a procedure in which a power controlis performed based on each available power indicator in a power transferphase according to an example.

FIG. 16 is a diagram illustrating a procedure in which a power controlis performed based on each available power indicator in a power transferphase according to an example.

FIG. 17 illustrates a protocol related to a transmission procedure ofthe RFR according to an embodiment.

FIG. 18 illustrates a packet structure according to an embodiment.

FIG. 19 illustrates a structure of the capability packet of the wirelesspower transmission apparatus including an available power indicatoraccording to an embodiment.

FIG. 20 illustrates a structure of the target power packet of thewireless power transmission apparatus according to an embodiment.

FIG. 21 illustrates a structure of the response packet of the wirelesspower reception apparatus according to an embodiment.

FIG. 22 illustrates a structure of the response packet of the wirelesspower transmission apparatus according to an embodiment.

FIG. 23 is a flowchart for the wireless power transmission apparatus totransmit information related to the available power indicator based onthe auxiliary transport protocol according to an embodiment.

FIG. 24a illustrates an ATX (or ATD) step performing the auxiliarytransport in detail according to an embodiment.

FIG. 24b illustrates an ATX (or ATD) step performing the auxiliarytransport in detail according to another embodiment.

FIG. 25 is a flowchart for the wireless power transmission apparatus totransmit information related to the available power indicator based onthe auxiliary transport protocol according to another embodiment.

FIG. 26 is an example of GR packet.

FIG. 27 is an example of RA packet.

FIG. 28 is an example of ACK packet.

FIG. 29 is an example of SOD/EOD packet.

FIG. 30 illustrates an ADT data transmission procedure according to anembodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The term “wireless power”, which will hereinafter be used in thisspecification, will be used to refer to an arbitrary form of energy thatis related to an electric field, a magnetic field, and anelectromagnetic field, which is transferred (or transmitted) from awireless power transmitter to a wireless power receiver without usingany physical electromagnetic conductors. The wireless power may also bereferred to as a wireless power signal, and this may refer to anoscillating magnetic flux that is enclosed by a primary coil and asecondary coil. For example, power conversion for wirelessly chargingdevices including mobile phones, cordless phones, iPods, MP3 players,headsets, and so on, within the system will be described in thisspecification. Generally, the basic principle of the wireless powertransfer technique includes, for example, all of a method oftransferring power by using magnetic coupling, a method of transferringpower by using radio frequency (RF), a method of transferring power byusing microwaves, and a method of transferring power by using ultrasound(or ultrasonic waves).

FIG. 1 is a block diagram of a wireless power system (10) according toan exemplary embodiment of the present invention.

Referring to FIG. 1, the wireless power system (10) include a wirelesspower transmitter (100) and a wireless power receiver (200).

The wireless power transmitter (100) is supplied with power from anexternal power source (S) and generates a magnetic field. The wirelesspower receiver (200) generates electric currents by using the generatedmagnetic field, thereby being capable of wirelessly receiving power.

Additionally, in the wireless power system (10), the wireless powertransmitter (100) and the wireless power receiver (200) may transceive(transmit and/or receive) diverse information that is required for thewireless power transfer. Herein, communication between the wirelesspower transmitter (100) and the wireless power receiver (200) may beperformed (or established) in accordance with any one of an in-bandcommunication, which uses a magnetic field that is used for the wirelesspower transfer (or transmission), and an out-band communication, whichuses a separate communication carrier.

Herein, the wireless power transmitter (100) may be provided as a fixedtype or a mobile (or portable) type. Examples of the fixed transmittertype may include an embedded type, which is embedded in in-door ceilingsor wall surfaces or embedded in furniture, such as tables, an implantedtype, which is installed in out-door parking lots, bus stops, subwaystations, and so on, or being installed in means of transportation, suchas vehicles or trains. The mobile (or portable) type wireless powertransmitter (100) may be implemented as a part of another device, suchas a mobile device having a portable size or weight or a cover of alaptop computer, and so on.

Additionally, the wireless power receiver (200) should be interpreted asa comprehensive concept including diverse home appliances and devicesthat are operated by being wirelessly supplied with power instead ofdiverse electronic devices being equipped with a battery and a powercable. Typical examples of the wireless power receiver (200) may includeportable terminals, cellular phones, smartphones, personal digitalassistants (PDAs), portable media players (PDPs), Wibro terminals,tablet PCs, phablet, laptop computers, digital cameras, navigationterminals, television, electronic vehicles (EVs), and so on.

In the wireless power system (10), one wireless power receiver (200) ora plurality of wireless power receivers may exist. Although it is shownin FIG. 1 that the wireless power transmitter (100) and the wirelesspower receiver (200) send and receive power to and from one another in aone-to-one correspondence (or relationship), as shown in FIG. 2, it isalso possible for one wireless power transmitter (100) to simultaneouslytransfer power to multiple wireless power receivers (200-1, 200-2, . . ., 200-M). Most particularly, in case the wireless power transfer (ortransmission) is performed by using a magnetic resonance method, onewireless power transmitter (100) may transfer power to multiple wirelesspower receivers (200-1, 200-2, . . . , 200-M) by using a synchronizedtransport (or transfer) method or a time-division transport (ortransfer) method.

Additionally, although it is shown in FIG. 1 that the wireless powertransmitter (100) directly transfers (or transmits) power to thewireless power receiver (200), the wireless power system (10) may alsobe equipped with a separate wireless power transceiver, such as a relayor repeater, for increasing a wireless power transfer distance betweenthe wireless power transmitter (100) and the wireless power receiver(200). In this case, power is delivered to the wireless powertransceiver from the wireless power transmitter (100), and, then, thewireless power transceiver may transfer the received power to thewireless power receiver (200).

Hereinafter, the terms wireless power receiver, power receiver, andreceiver, which are mentioned in this specification, will refer to thewireless power receiver (200). Also, the terms wireless powertransmitter, power transmitter, and transmitter, which are mentioned inthis specification, will refer to the wireless power transmitter (100).

FIG. 3 shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transmission system.

As shown in FIG. 3, the electronic devices included in the wirelesspower transmission system are sorted in accordance with the amount oftransmitted power and the amount of received power. Referring to FIG. 3,wearable devices, such as smart watches, smart glasses, head mounteddisplays (HMDs), smart rings, and so on, and mobile electronic devices(or portable electronic devices), such as earphones, remote controllers,smartphones, PDAs, tablet PCs, and so on, may adopt a low-power(approximately 5 W or less or approximately 20 W or less) wirelesscharging method.

Small-sized/Mid-sized electronic devices, such as laptop computers,robot vacuum cleaners, TV receivers, audio devices, vacuum cleaners,monitors, and so on, may adopt a mid-power (approximately 50 W or lessor approximately 200 W or less) wireless charging method. Kitchenappliances, such as mixers, microwave ovens, electric rice cookers, andso on, and personal transportation devices (or other electric devices ormeans of transportation), such as powered wheelchairs, powered kickscooters, powered bicycles, electric cars, and so on may adopt ahigh-power (approximately 2 kW or less or approximately 22 kW or less)wireless charging method.

The electric devices or means of transportation, which are describedabove (or shown in FIG. 1) may each include a wireless power receiver,which will hereinafter be described in detail. Therefore, theabove-described electric devices or means of transportation may becharged (or re-charged) by wirelessly receiving power from a wirelesspower transmitter.

Hereinafter, although the present invention will be described based on amobile device adopting the wireless power charging method, this ismerely exemplary. And, therefore, it shall be understood that thewireless charging method according to the present invention may beapplied to diverse electronic devices.

The wireless power transmitter and the wireless power receiver mayprovide a highly convenient user experience and user experience (UX/UI).More specifically, a smart wireless charging service may be provided.The smart wireless charging service may be implemented based on theUX/UI of a smartphone including a wireless power transmitter. For suchapplication, an interface between the processor and the wireless powerreceiver of the smartphone authorizes a “drop and play” two-waycommunication between the wireless power transmitter and the wirelesspower receiver.

For example, the user may experience a smart wireless charging servicein a hotel. When the user enters his (or her) room and places his (orher) smartphone on a wireless charger, which is provided in the hotelroom, the wireless charging device transmits wireless power to thesmartphone, and the smartphone receives the transmitted wireless power.During this process, information related to the wireless chargingservice is transmitted to the smartphone. If the smartphone detects thatit is being placed on a wireless charger, if the smartphone detects thereception of wireless power, or if the smartphone detects receivesinformation related to a smart wireless charging service from thewireless charger, the smartphone enters a phase (or state) of inquiringan agreement (opt-in) to an additional feature. For this, the smartphonemay display a message on a screen by using a method that includes analarm tone or by using a method that does not include an alarm tone. Anexample of the message may include phrases, such as “Welcome to ###hotel. Select “Yes” to activate smart charging functions: Yes|NoThanks.” The smartphone receives the user input selecting any one of Yesand No Thanks, and the next procedure that is selected by the user isperformed. If Yes is selected, the smartphone transmits thecorresponding information to the wireless charger. Thereafter, thesmartphone and the wireless charger collectively perform the smartcharging function.

The smart wireless charging service may also include receiving anautomatic input Wi-Fi credentials. For example, the wireless chargertransmits Wi-Fi credentials to the smartphone, and the smartphoneexecutes a suitable application and automatically inputs the Wi-Ficredentials that are received from the wireless charger.

The smart wireless charging service may also include executing a hotelapplication providing hotel promotion information, performing remotecontrolled check-in/check-out, or acquiring contact information.

As another example, the user may experience a smart wireless chargingservice in a car. When the user gets in a car (or vehicle) and placeshis (or her) smartphone on a wireless charger, which is provided in thevehicle, the wireless charging device transmits wireless power to thesmartphone, and the smartphone receives the transmitted wireless power.During this process, information related to the wireless chargingservice is transmitted to the smartphone. If the smartphone detects thatit is being placed on a wireless charger, if the smartphone detects thereception of wireless power, or if the smartphone detects receivesinformation related to a smart wireless charging service from thewireless charger, the smartphone enters a phase (or state) of inquiringthe identity of the user.

In this state, the smartphone may be automatically connected to thevehicle via Wi-Fi or Bluetooth. Then, the smartphone may display amessage on a screen by using a method that includes an alarm tone or byusing a method that does not include an alarm tone. An example of themessage may include phrases, such as “Welcome to your car. Select “Yes”to synch device with in-car controls: Yes|No Thanks.” The smartphonereceives the user input selecting any one of Yes and No Thanks, and thenext procedure that is selected by the user is performed. If Yes isselected, the smartphone transmits the corresponding information to thewireless charger. Thereafter, by operating an application/displaysoftware within the vehicle, the smartphone and the wireless charger maycollectively perform a smart control function within the vehicle. Theuser may enjoy listening to music as desired and may also confirm his(or her) regular map location. An application/display software withinthe vehicle may include a capability of providing synchronized accessfor pedestrians.

As yet another example, the user may experience a smart wirelesscharging service in his (or her) home. When the user enters his (or her)room at home and places his (or her) smartphone on a wireless charger,the wireless charging device transmits wireless power to the smartphone,and the smartphone receives the transmitted wireless power. During thisprocess, information related to the wireless charging service istransmitted to the smartphone. If the smartphone detects that it isbeing placed on a wireless charger, if the smartphone detects thereception of wireless power, or if the smartphone detects receivesinformation related to a smart wireless charging service from thewireless charger, the smartphone enters a phase (or state) of inquiringan agreement (opt-in) to an additional feature. For this, the smartphonemay display a message on a screen by using a method that includes analarm tone or by using a method that does not include an alarm tone. Anexample of the message may include phrases, such as “Hi xxx, Would youlike to activate night mode and secure the building?: Yes|No Thanks.”The smartphone receives the user input selecting any one of Yes and NoThanks, and the next procedure that is selected by the user isperformed. If Yes is selected, the smartphone transmits thecorresponding information to the wireless charger. Thereafter, thesmartphone and the wireless charger at least acknowledges (orrecognizes) a pattern of the user and may recommend the user to lock thedoors and windows or to turn off the lights, or to set up an alarm.

A standard for the wireless power transfer (or transmission) includes awireless power consortium (WPC), an air fuel alliance (AFA), and a powermatters alliance (PMA).

The WPC standard defines a baseline power profile (BPP) and an extendedpower profile (EPP). The BPP is related to a wireless power transmitterand a wireless power receiver supporting a power transfer of 5 W, andthe EPP is related to a wireless power transmitter and a wireless powerreceiver supporting the transfer of a power range greater than 5 W andless than 30 W.

Diverse wireless power transmitters and wireless power receivers eachusing a different power level may be covered by each standard and may besorted by different power classes or categories.

For example, the WPC may categorize (or sort) the wireless powertransmitters and the wireless power receivers as PC−1, PC0, PC1, andPC2, and the WPC may provide a standard document (or specification) foreach power class (PC). The PC−1 standard relates to wireless powertransmitters and receivers providing a guaranteed power of less than 5W. The application of PC−1 includes wearable devices, such as smartwatches.

The PC0 standard relates to wireless power transmitters and receiversproviding a guaranteed power of 5 W. The PC0 standard includes an EPPhaving a guaranteed power ranges that extends to 30 W. Although in-band(IB) communication corresponds to a mandatory communication protocol ofPC0, out-of-band (OBB) communication that is used as an optional backupchannel may also be used for PC0. The wireless power receiver may beidentified by setting up an OOB flag, which indicates whether or not theOOB is supported, within a configuration packet. A wireless powertransmitter supporting the OOB may enter an OOB handover phase bytransmitting a bit-pattern for an OOB handover as a response to theconfiguration packet. The response to the configuration packet maycorrespond to an NAK, an ND, or an 8-bit pattern that is newly defined.The application of the PC0 includes smartphones.

The PC1 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 30 W to 150 W. OOB correspondsto a mandatory communication channel for PC1, and IB is used forinitialization and link establishment to OOB. The wireless powertransmitter may enter an OOB handover phase by transmitting abit-pattern for an OOB handover as a response to the configurationpacket. The application of the PC1 includes laptop computers or powertools.

The PC2 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 200 W to 2 kW, and itsapplication includes kitchen appliances.

As described above, the PCs may be differentiated in accordance with therespective power levels. And, information on whether or not thecompatibility between the same PCs is supported may be optional ormandatory. Herein, the compatibility between the same PCs indicates thatpower transmission/reception between the same PCs is possible. Forexample, in case a wireless power transmitter corresponding to PC x iscapable of performing charging of a wireless power receiver having thesame PC x, it may be understood that compatibility is maintained betweenthe same PCs. Similarly, compatibility between different PCs may also besupported. Herein, the compatibility between different PCs indicatesthat power transmission/reception between different PCs is alsopossible. For example, in case a wireless power transmittercorresponding to PC x is capable of performing charging of a wirelesspower receiver having PC y, it may be understood that compatibility ismaintained between the different PCs.

The support of compatibility between PCs corresponds to an extremelyimportant issue in the aspect of user experience and establishment ofinfrastructure. Herein, however, diverse problems, which will bedescribed below, exist in maintaining the compatibility between PCs.

In case of the compatibility between the same PCs, for example, in caseof a wireless power receiver using a lap-top charging method, whereinstable charging is possible only when power is continuously transferred,even if its respective wireless power transmitter has the same PC, itmay be difficult for the corresponding wireless power receiver to stablyreceive power from a wireless power transmitter of the power toolmethod, which transfers power non-continuously. Additionally, in case ofthe compatibility between different PCs, for example, in case a wirelesspower transmitter having a minimum guaranteed power of 200 W transferspower to a wireless power receiver having a maximum guaranteed power of5 W, the corresponding wireless power receiver may be damaged due to anovervoltage. As a result, it may be inappropriate (or difficult) to usethe PS as an index/reference standard representing/indicating thecompatibility.

According to the above-described exemplary embodiment of the presentinvention, in the wireless power transmitting method and wireless powertransmitter, or in the wireless power receiving method and wirelesspower receiver, not all of the configuration elements or process stepsare mandatory. And, therefore, all or part of the above-describedconfiguration elements or process steps of the wireless powertransmitting method and wireless power transmitter or the wireless powerreceiving method and wireless power receiver may be included andperformed. Additionally, the exemplary embodiments of the wireless powertransmitting method and wireless power transmitter or the wireless powerreceiving method and wireless power receiver may be performed andimplemented by being combined with one another. Furthermore, each of theabove-described configuration elements or process steps is notmandatorily required to be performed in accordance with theabove-described order. And, therefore, it may be possible to perform aprocess step that was described later prior to a process step, which hasbeen described above to precede the later process.

Hereinafter, ‘profiles’ will be newly defined based on indexes/referencestandards representing/indicating the compatibility. More specifically,it may be understood that by maintaining compatibility between wirelesspower transmitters and receivers having the same ‘profile’, stable powertransmission/reception may be performed, and that powertransmission/reception between wireless power transmitters and receivershaving different ‘profiles’ cannot be performed. The ‘profiles’ may bedefined in accordance with whether or not compatibility is possibleand/or the application regardless of (or independent from) the powerclass.

For example, the profile may be sorted into 4 different categories, suchas i) Mobile, ii) Power tool, iii) Kitchen, and iv) Wearable.

In case of the ‘Mobile’ profile, the PC may be defined as PC0 and/orPC1, the communication protocol/method may be defined as IB and OOBcommunication, and the operation frequency may be defined as 87 to 205kHz, and smartphones, laptop computers, and so on, may exist as theexemplary application.

In case of the ‘Power tool’ profile, the PC may be defined as PC1, thecommunication protocol/method may be defined as IB communication, andthe operation frequency may be defined as 87 to 145 kHz, and powertools, and so on, may exist as the exemplary application.

In case of the ‘Kitchen’ profile, the PC may be defined as PC2, thecommunication protocol/method may be defined as NFC-based communication,and the operation frequency may be defined as less than 100 kHz, andkitchen/home appliances, and so on, may exist as the exemplaryapplication.

In case of the ‘Wearable’ profile, the PC may be defined as PC−1, thecommunication protocol/method may be defined as IB communication, andthe operation frequency may be defined as 87 to 205 kHz, and wearabledevices that are worn by the users, and so on, may exist as theexemplary application.

It may be mandatory to maintain compatibility between the same profiles,and it may be optional to maintain compatibility between differentprofiles.

The above-described profiles (Mobile profile, Power tool profile,Kitchen profile, and Wearable profile) may be generalized and expressedas first to n^(th) profile, and a new profile may be added/replaced inaccordance with the WPC standard and the exemplary embodiment.

In case the profile is defined as described above, the wireless powertransmitter may optionally perform power transmission only to thewireless power receiving corresponding to the same profile as thewireless power transmitter, thereby being capable of performing a morestable power transmission. Additionally, since the load (or burden) ofthe wireless power transmitter may be reduced and power transmission isnot attempted to a wireless power receiver for which compatibility isnot possible, the risk of damage in the wireless power receiver may bereduced.

PC1 of the ‘Mobile’ profile may be defined by being derived from anoptional extension, such as OOB, based on PC0. And, the ‘Power tool’profile may be defined as a simply modified version of the PC1 ‘Mobile’profile. Additionally, up until now, although the profiles have beendefined for the purpose of maintaining compatibility between the sameprofiles, in the future, the technology may be evolved to a level ofmaintaining compatibility between different profiles. The wireless powertransmitter or the wireless power receiver may notify (or announce) itsprofile to its counterpart by using diverse methods.

In the AFA standard, the wireless power transmitter is referred to as apower transmitting unit (PTU), and the wireless power receiver isreferred to as a power receiving unit (PRU). And, the PTU is categorizedto multiple classes, as shown in Table 1, and the PRU is categorized tomultiple classes, as shown in Table 2.

TABLE 1 Minimum value for a Minimum category maximum number of P_(TX)_(—) _(IN) _(—) _(MAX) support requirement supported devices Class 1  2W 1x Category 1 1x Category 1 Class 2 10 W 1x Category 3 2x Category 2Class 3 16 W 1x Category 4 2x Category 3 Class 4 33 W 1x Category 5 3xCategory 3 Class 5 50 W 1x Category 6 4x Category 3 Class 6 70 W 1xCategory 7 5x Category 3

TABLE 2 PRU P_(RX) _(—) _(OUT) _(—) _(MAX′) Exemplary applicationCategory 1 TBD Bluetooth headset Category 2 3.5 W  Feature phoneCategory 3 6.5 W  Smartphone Category 4 13 W Tablet PC, Phablet Category5 25 W Small form factor laptop Category 6 37.5 W   General laptopCategory 7 50 W Home appliance

As shown in Table 1, a maximum output power capability of Class n PTUmay be equal to or greater than the P_(TX_IN_MAX) of the correspondingclass. The PRU cannot draw a power that is higher than the power levelspecified in the corresponding category.

FIG. 4 is a block diagram of a wireless power transmission systemaccording to another exemplary embodiment of the present invention.

Referring to FIG. 4, the wireless power transmission system (10)includes a mobile device (450), which wirelessly receives power, and abase station (400), which wirelessly transmits power.

As a device providing induction power or resonance power, the basestation (400) may include at least one of a wireless power transmitter(100) and a system unit (405). The wireless power transmitter (100) maytransmit induction power or resonance power and may control thetransmission. The wireless power transmitter (100) may include a powerconversion unit (110) converting electric energy to a power signal bygenerating a magnetic field through a primary coil (or primary coils),and a communications & control unit (120) controlling the communicationand power transfer between the wireless power receiver (200) in order totransfer power at an appropriate (or suitable) level. The system unit(405) may perform input power provisioning, controlling of multiplewireless power transmitters, and other operation controls of the basestation (400), such as user interface control.

The primary coil may generate an electromagnetic field by using analternating current power (or voltage or current). The primary coil issupplied with an alternating current power (or voltage or current) of aspecific frequency, which is being outputted from the power conversionunit (110). And, accordingly, the primary coil may generate a magneticfield of the specific frequency. The magnetic field may be generated ina non-radial shape or a radial shape. And, the wireless power receiver(200) receives the generated magnetic field and then generates anelectric current. In other words, the primary coil wirelessly transmitspower.

In the magnetic induction method, a primary coil and a secondary coilmay have randomly appropriate shapes. For example, the primary coil andthe secondary coil may correspond to copper wire being wound around ahigh-permeability formation, such as ferrite or a non-crystalline metal.The primary coil may also be referred to as a primary core, a primarywinding, a primary loop antenna, and so on. Meanwhile, the secondarycoil may also be referred to as a secondary core, a secondary winding, asecondary loop antenna, a pickup antenna, and so on.

In case of using the magnetic resonance method, the primary coil and thesecondary coil may each be provided in the form of a primary resonanceantenna and a secondary resonance antenna. The resonance antenna mayhave a resonance structure including a coil and a capacitor. At thispoint, the resonance frequency of the resonance antenna may bedetermined by the inductance of the coil and a capacitance of thecapacitor. Herein, the coil may be formed to have a loop shape. And, acore may be placed inside the loop. The core may include a physicalcore, such as a ferrite core, or an air core.

The energy transmission (or transfer) between the primary resonanceantenna and the second resonance antenna may be performed by a resonancephenomenon occurring in the magnetic field. When a near fieldcorresponding to a resonance frequency occurs in a resonance antenna,and in case another resonance antenna exists near the correspondingresonance antenna, the resonance phenomenon refers to a highly efficientenergy transfer occurring between the two resonance antennas that arecoupled with one another. When a magnetic field corresponding to theresonance frequency is generated between the primary resonance antennaand the secondary resonance antenna, the primary resonance antenna andthe secondary resonance antenna resonate with one another. And,accordingly, in a general case, the magnetic field is focused toward thesecond resonance antenna at a higher efficiency as compared to a casewhere the magnetic field that is generated from the primary antenna isradiated to a free space. And, therefore, energy may be transferred tothe second resonance antenna from the first resonance antenna at a highefficiency. The magnetic induction method may be implemented similarlyto the magnetic resonance method. However, in this case, the frequencyof the magnetic field is not required to be a resonance frequency.Nevertheless, in the magnetic induction method, the loops configuringthe primary coil and the secondary coil are required to match oneanother, and the distance between the loops should be very close-ranged.

Although it is not shown in the drawing, the wireless power transmitter(100) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (120) may transmit and/or receiveinformation to and from the wireless power receiver (200). Thecommunications & control unit (120) may include at least one of an IBcommunication module and an OOB communication module.

The IB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (120) mayperform in-band (IB) communication by loading information in themagnetic wave and by transmitting the information through the primarycoil or by receiving a magnetic wave carrying information through theprimary coil. At this point, the communications & control unit (120) mayload information in the magnetic wave or may interpret the informationthat is carried by the magnetic wave by using a modulation scheme, suchas binary phase shift keying (BPSK) or amplitude shift keying (ASK), andso on, or a coding scheme, such as Manchester coding ornon-return-to-zero level (NZR-L) coding, and so on. By using theabove-described IB communication, the communications & control unit(120) may transmit and/or receive information to distances of up toseveral meters at a data transmission rate of several kbps.

The OOB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (120) may be provided to a near field communication module.Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (120) may control the overalloperations of the wireless power transmitter (100). The communications &control unit (120) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power transmitter (100).

The communications & control unit (120) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (120) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (120) may beprovided as a program that operates the communications & control unit(120).

By controlling the operation point, the communications & control unit(120) may control the transmitted power. The operation point that isbeing controlled may correspond to a combination of a frequency (orphase), a duty cycle, a duty ratio, and a voltage amplitude. Thecommunications & control unit (120) may control the transmitted power byadjusting any one of the frequency (or phase), the duty cycle, the dutyratio, and the voltage amplitude. Additionally, the wireless powertransmitter (100) may supply a consistent level of power, and thewireless power receiver (200) may control the level of received power bycontrolling the resonance frequency.

The mobile device (450) includes a wireless power receiver (200)receiving wireless power through a secondary coil, and a load (455)receiving and storing the power that is received by the wireless powerreceiver (200) and supplying the received power to the device.

The wireless power receiver (200) may include a power pick-up unit (210)and a communications & control unit (220). The power pick-up unit (210)may receive wireless power through the secondary coil and may convertthe received wireless power to electric energy. The power pick-up unit(210) rectifies the alternating current (AC) signal, which is receivedthrough the secondary coil, and converts the rectified signal to adirect current (DC) signal. The communications & control unit (220) maycontrol the transmission and reception of the wireless power (transferand reception of power).

The secondary coil may receive wireless power that is being transmittedfrom the wireless power transmitter (100). The secondary coil mayreceive power by using the magnetic field that is generated in theprimary coil. Herein, in case the specific frequency corresponds aresonance frequency, magnetic resonance may occur between the primarycoil and the secondary coil, thereby allowing power to be transferredwith greater efficiency.

Although it is not shown in FIG. 4, the communications & control unit(220) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (220) may transmit and/or receiveinformation to and from the wireless power transmitter (100). Thecommunications & control unit (220) may include at least one of an IBcommunication module and an OOB communication module.

The IB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (220) mayperform IB communication by loading information in the magnetic wave andby transmitting the information through the secondary coil or byreceiving a magnetic wave carrying information through the secondarycoil. At this point, the communications & control unit (120) may loadinformation in the magnetic wave or may interpret the information thatis carried by the magnetic wave by using a modulation scheme, such asbinary phase shift keying (BPSK) or amplitude shift keying (ASK), and soon, or a coding scheme, such as Manchester coding or non-return-to-zerolevel (NZR-L) coding, and so on. By using the above-described IBcommunication, the communications & control unit (220) may transmitand/or receive information to distances of up to several meters at adata transmission rate of several kbps.

The OOB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (220) may be provided to a near field communication module.

Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (220) may control the overalloperations of the wireless power receiver (200). The communications &control unit (220) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power receiver (200).

The communications & control unit (220) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (220) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (220) may beprovided as a program that operates the communications & control unit(220).

The load (455) may correspond to a battery. The battery may store energyby using the power that is being outputted from the power pick-up unit(210). Meanwhile, the battery is not mandatorily required to be includedin the mobile device (450). For example, the battery may be provided asa detachable external feature. As another example, the wireless powerreceiver may include an operating means that can execute diversefunctions of the electronic device instead of the battery.

As shown in the drawing, although the mobile device (450) is illustratedto be included in the wireless power receiver (200) and the base station(400) is illustrated to be included in the wireless power transmitter(100), in a broader meaning, the wireless power receiver (200) may beidentified (or regarded) as the mobile device (450), and the wirelesspower transmitter (100) may be identified (or regarded) as the basestation (400).

Hereinafter, the coil or coil unit includes a coil and at least onedevice being approximate to the coil, and the coil or coil unit may alsobe referred to as a coil assembly, a coil cell, or a cell.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

Referring to FIG. 5, the power transmission (or transfer) from thewireless power transmitter to the wireless power receiver according toan exemplary embodiment of the present invention may be broadly dividedinto a selection phase (510), a ping phase (520), an identification andconfiguration phase (530), a negotiation phase (540), a calibrationphase (550), a power transfer phase (560), and a renegotiation phase(570).

If a specific error or a specific event is detected when the powertransfer is initiated or while maintaining the power transfer, theselection phase (510) may include a shifting phase (or step)-referencenumerals S502, S504, S508, S510, and S512. Herein, the specific error orspecific event will be specified in the following description.Additionally, during the selection phase (510), the wireless powertransmitter may monitor whether or not an object exists on an interfacesurface. If the wireless power transmitter detects that an object isplaced on the interface surface, the process step may be shifted to theping phase (520). During the selection phase (510), the wireless powertransmitter may transmit an analog ping having an extremely short pulseand may detect whether or not an object exists within an active area ofthe interface surface based on a current change in the transmitting coilor the primary coil.

In case an object is sensed (or detected) in the selection phase (510),the wireless power transmitter may measure a quality factor of awireless power resonance circuit (e.g., power transmission coil and/orresonance capacitor). According to the exemplary embodiment of thepresent invention, during the selection phase (510), the wireless powertransmitter may measure the quality factor in order to determine whetheror not a foreign object exists in the charging area along with thewireless power receiver. In the coil that is provided in the wirelesspower transmitter, inductance and/or components of the series resistancemay be reduced due to a change in the environment, and, due to suchdecrease, a value of the quality factor may also be decreased. In orderto determine the presence or absence of a foreign object by using themeasured quality factor value, the wireless power transmitter mayreceive from the wireless power receiver a reference quality factorvalue, which is measured in advance in a state where no foreign objectis placed within the charging area. The wireless power transmitter maydetermine the presence or absence of a foreign object by comparing themeasured quality factor value with the reference quality factor value,which is received during the negotiation phase (540). However, in caseof a wireless power receiver having a low reference quality factorvalue—e.g., depending upon its type, purpose, characteristics, and soon, the wireless power receiver may have a low reference quality factorvalue-in case a foreign object exists, since the difference between thereference quality factor value and the measured quality factor value issmall (or insignificant), a problem may occur in that the presence ofthe foreign object cannot be easily determined. Accordingly, in thiscase, other determination factors should be further considered, or thepresent or absence of a foreign object should be determined by usinganother method.

According to another exemplary embodiment of the present invention, incase an object is sensed (or detected) in the selection phase (510), inorder to determine whether or not a foreign object exists in thecharging area along with the wireless power receiver, the wireless powertransmitter may measure the quality factor value within a specificfrequency area (e.g., operation frequency area). In the coil that isprovided in the wireless power transmitter, inductance and/or componentsof the series resistance may be reduced due to a change in theenvironment, and, due to such decrease, the resonance frequency of thecoil of the wireless power transmitter may be changed (or shifted). Morespecifically, a quality factor peak frequency that corresponds to afrequency in which a maximum quality factor value is measured within theoperation frequency band may be moved (or shifted).

In the ping phase (520), if the wireless power transmitter detects thepresence of an object, the transmitter activates (or Wakes up) areceiver and transmits a digital ping for identifying whether or not thedetected object corresponds to the wireless power receiver. During theping phase (520), if the wireless power transmitter fails to receive aresponse signal for the digital ping—e.g., a signal intensitypacket-from the receiver, the process may be shifted back to theselection phase (510). Additionally, in the ping phase (520), if thewireless power transmitter receives a signal indicating the completionof the power transfer—e.g., charging complete packet-from the receiver,the process may be shifted back to the selection phase (510).

If the ping phase (520) is completed, the wireless power transmitter mayshift to the identification and configuration phase (530) foridentifying the receiver and for collecting configuration and statusinformation.

In the identification and configuration phase (530), if the wirelesspower transmitter receives an unwanted packet (i.e., unexpected packet),or if the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., out of time), or if a packettransmission error occurs (i.e., transmission error), or if a powertransfer contract is not configured (i.e., no power transfer contract),the wireless power transmitter may shift to the selection phase (510).

The wireless power transmitter may confirm (or verify) whether or notits entry to the negotiation phase (540) is needed based on aNegotiation field value of the configuration packet, which is receivedduring the identification and configuration phase (530). Based on theverified result, in case a negotiation is needed, the wireless powertransmitter enters the negotiation phase (540) and may then perform apredetermined FOD detection procedure. Conversely, in case a negotiationis not needed, the wireless power transmitter may immediately enter thepower transfer phase (560).

In the negotiation phase (540), the wireless power transmitter mayreceive a Foreign Object Detection (FOD) status packet that includes areference quality factor value. Or, the wireless power transmitter mayreceive an FOD status packet that includes a reference peak frequencyvalue. Alternatively, the wireless power transmitter may receive astatus packet that includes a reference quality factor value and areference peak frequency value. At this point, the wireless powertransmitter may determine a quality coefficient threshold value for FOdetection based on the reference quality factor value. The wirelesspower transmitter may determine a peak frequency threshold value for FOdetection based on the reference peak frequency value.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined quality coefficientthreshold value for FO detection and the currently measured qualityfactor value (i.e., the quality factor value that was measured beforethe ping phase), and, then, the wireless power transmitter may controlthe transmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, the present invention will not be limited only to this.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined peak frequency thresholdvalue for FO detection and the currently measured peak frequency value(i.e., the peak frequency value that was measured before the pingphase), and, then, the wireless power transmitter may control thetransmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, the present invention will not be limited only to this.

In case the FO is detected, the wireless power transmitter may return tothe selection phase (510). Conversely, in case the FO is not detected,the wireless power transmitter may proceed to the calibration phase(550) and may, then, enter the power transfer phase (560). Morespecifically, in case the FO is not detected, the wireless powertransmitter may determine the intensity of the received power that isreceived by the receiving end during the calibration phase (550) and maymeasure power loss in the receiving end and the transmitting end inorder to determine the intensity of the power that is transmitted fromthe transmitting end. In other words, during the calibration phase(550), the wireless power transmitter may estimate the power loss basedon a difference between the transmitted power of the transmitting endand the received power of the receiving end. The wireless powertransmitter according to the exemplary embodiment of the presentinvention may calibrate the threshold value for the FOD detection byapplying the estimated power loss.

In the power transfer phase (560), in case the wireless powertransmitter receives an unwanted packet (i.e., unexpected packet), or incase the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., time-out), or in case a violation ofa predetermined power transfer contract occurs (i.e., power transfercontract violation), or in case charging is completed, the wirelesspower transmitter may shift to the selection phase (510).

Additionally, in the power transfer phase (560), in case the wirelesspower transmitter is required to reconfigure the power transfer contractin accordance with a status change in the wireless power transmitter,the wireless power transmitter may shift to the renegotiation phase(570). At this point, if the renegotiation is successfully completed,the wireless power transmitter may return to the power transfer phase(560).

The above-described power transfer contract may be configured based onthe status and characteristic information of the wireless powertransmitter and receiver. For example, the wireless power transmitterstatus information may include information on a maximum amount oftransmittable power, information on a maximum number of receivers thatcan be accommodated, and so on. And, the receiver status information mayinclude information on the required power, and so on.

FIG. 6 shows a power control method according to an exemplary embodimentof the present invention.

As shown in FIG. 6, in the power transfer phase (560), by alternatingthe power transmission and/or reception and communication, the wirelesspower transmitter (100) and the wireless power receiver (200) maycontrol the amount (or size) of the power that is being transferred. Thewireless power transmitter and the wireless power receiver operate at aspecific control point. The control point indicates a combination of thevoltage and the electric current that are provided from the output ofthe wireless power receiver, when the power transfer is performed.

More specifically, the wireless power receiver selects a desired controlpoint, a desired output current/voltage, a temperature at a specificlocation of the mobile device, and so on, and additionally determines anactual control point at which the receiver is currently operating. Thewireless power receiver calculates a control error value by using thedesired control point and the actual control point, and, then, thewireless power receiver may transmit the calculated control error valueto the wireless power transmitter as a control error packet.

Also, the wireless power transmitter may configure/control a newoperation point-amplitude, frequency, and duty cycle-by using thereceived control error packet, so as to control the power transfer.Therefore, the control error packet may be transmitted/received at aconstant time interval during the power transfer phase, and, accordingto the exemplary embodiment, in case the wireless power receiverattempts to reduce the electric current of the wireless powertransmitter, the wireless power receiver may transmit the control errorpacket by setting the control error value to a negative number. And, incase the wireless power receiver intends to increase the electriccurrent of the wireless power transmitter, the wireless power receivertransmit the control error packet by setting the control error value toa positive number. During the induction mode, by transmitting thecontrol error packet to the wireless power transmitter as describedabove, the wireless power receiver may control the power transfer.

In the resonance mode, which will hereinafter be described in detail,the device may be operated by using a method that is different from theinduction mode. In the resonance mode, one wireless power transmittershould be capable of serving a plurality of wireless power receivers atthe same time. However, in case of controlling the power transfer justas in the induction mode, since the power that is being transferred iscontrolled by a communication that is established with one wirelesspower receiver, it may be difficult to control the power transfer ofadditional wireless power receivers. Therefore, in the resonance modeaccording to the present invention, a method of controlling the amountof power that is being received by having the wireless power transmittercommonly transfer (or transmit) the basic power and by having thewireless power receiver control its own resonance frequency.Nevertheless, even during the operation of the resonance mode, themethod described above in FIG. 6 will not be completely excluded. And,additional control of the transmitted power may be performed by usingthe method of FIG. 6.

FIG. 7 is a block diagram of a wireless power transmitter according toanother exemplary embodiment of the present invention. This may belongto a wireless power transmission system that is being operated in themagnetic resonance mode or the shared mode. The shared mode may refer toa mode performing a several-for-one (or one-to-many) communication andcharging between the wireless power transmitter and the wireless powerreceiver. The shared mode may be implemented as a magnetic inductionmethod or a resonance method.

Referring to FIG. 7, the wireless power transmitter (700) may include atleast one of a cover (720) covering a coil assembly, a power adapter(730) supplying power to the power transmitter (740), a powertransmitter (740) transmitting wireless power, and a user interface(750) providing information related to power transfer processing andother related information. Most particularly, the user interface (750)may be optionally included or may be included as another user interface(750) of the wireless power transmitter (700).

The power transmitter (740) may include at least one of a coil assembly(760), an impedance matching circuit (770), an inverter (780), acommunication unit (790), and a control unit (710).

The coil assembly (760) includes at least one primary coil generating amagnetic field. And, the coil assembly (760) may also be referred to asa coil cell.

The impedance matching circuit (770) may provide impedance matchingbetween the inverter and the primary coil(s). The impedance matchingcircuit (770) may generate resonance from a suitable frequency thatboosts the electric current of the primary coil(s). In a multi-coilpower transmitter (740), the impedance matching circuit may additionallyinclude a multiplex that routes signals from the inverter to a subset ofthe primary coils. The impedance matching circuit may also be referredto as a tank circuit.

The impedance matching circuit (770) may include a capacitor, aninductor, and a switching device that switches the connection betweenthe capacitor and the inductor. The impedance matching may be performedby detecting a reflective wave of the wireless power that is beingtransferred (or transmitted) through the coil assembly (760) and byswitching the switching device based on the detected reflective wave,thereby adjusting the connection status of the capacitor or the inductoror adjusting the capacitance of the capacitor or adjusting theinductance of the inductor. In some cases, the impedance matching may becarried out even though the impedance matching circuit (770) is omitted.This specification also includes an exemplary embodiment of the wirelesspower transmitter (700), wherein the impedance matching circuit (770) isomitted.

The inverter (780) may convert a DC input to an AC signal. The inverter(780) may be operated as a half-bridge inverter or a full-bridgeinverter in order to generate a pulse wave and a duty cycle of anadjustable frequency. Additionally, the inverter may include a pluralityof stages in order to adjust input voltage levels.

The communication unit (790) may perform communication with the powerreceiver. The power receiver performs load modulation in order tocommunicate requests and information corresponding to the powertransmitter. Therefore, the power transmitter (740) may use thecommunication unit (790) so as to monitor the amplitude and/or phase ofthe electric current and/or voltage of the primary coil in order todemodulate the data being transmitted from the power receiver.

Additionally, the power transmitter (740) may control the output powerto that the data can be transferred through the communication unit (790)by using a Frequency Shift Keying (FSK) method, and so on.

The control unit (710) may control communication and power transfer (ordelivery) of the power transmitter (740). The control unit (710) maycontrol the power transfer by adjusting the above-described operationpoint. The operation point may be determined by, for example, at leastany one of the operation frequency, the duty cycle, and the inputvoltage.

The communication unit (790) and the control unit (710) may each beprovided as a separate unit/device/chipset or may be collectivelyprovided as one unit/device/chipset.

FIG. 8 shows a wireless power receiver according to another exemplaryembodiment of the present invention. This may belong to a wireless powertransmission system that is being operated in the magnetic resonancemode or the shared mode.

Referring to FIG. 8, the wireless power receiver (800) may include atleast one of a user interface (820) providing information related topower transfer processing and other related information, a powerreceiver (830) receiving wireless power, a load circuit (840), and abase (850) supporting and covering the coil assembly. Most particularly,the user interface (820) may be optionally included or may be includedas another user interface (820) of the wireless power receiver (800).

The power receiver (830) may include at least one of a power converter(860), an impedance matching circuit (870), a coil assembly (880), acommunication unit (890), and a control unit (810).

The power converter (860) may convert the AC power that is received fromthe secondary coil to a voltage and electric current that are suitablefor the load circuit. According to an exemplary embodiment, the powerconverter (860) may include a rectifier. The rectifier may rectify thereceived wireless power and may convert the power from an alternatingcurrent (AC) to a direct current (DC). The rectifier may convert thealternating current to the direct current by using a diode or atransistor, and, then, the rectifier may smooth the converted current byusing the capacitor and resistance. Herein, a full-wave rectifier, ahalf-wave rectifier, a voltage multiplier, and so on, that areimplemented as a bridge circuit may be used as the rectifier.Additionally, the power converter may adapt a reflected impedance of thepower receiver.

The impedance matching circuit (870) may provide impedance matchingbetween a combination of the power converter (860) and the load circuit(840) and the secondary coil. According to an exemplary embodiment, theimpedance matching circuit may generate a resonance of approximately 100kHz, which can reinforce the power transfer. The impedance matchingcircuit (870) may include a capacitor, an inductor, and a switchingdevice that switches the combination of the capacitor and the inductor.The impedance matching may be performed by controlling the switchingdevice of the circuit that configured the impedance matching circuit(870) based on the voltage value, electric current value, power value,frequency value, and so on, of the wireless power that is beingreceived. In some cases, the impedance matching may be carried out eventhough the impedance matching circuit (870) is omitted. Thisspecification also includes an exemplary embodiment of the wirelesspower receiver (200), wherein the impedance matching circuit (870) isomitted.

The coil assembly (880) includes at least one secondary coil, and,optionally, the coil assembly (880) may further include an elementshielding the metallic part of the receiver from the magnetic field.

The communication unit (890) may perform load modulation in order tocommunicate requests and other information to the power transmitter.

For this, the power receiver (830) may perform switching of theresistance or capacitor so as to change the reflected impedance.

The control unit (810) may control the received power. For this, thecontrol unit (810) may determine/calculate a difference between anactual operation point and a desired operation point of the powerreceiver (830). Thereafter, by performing a request for adjusting thereflected impedance of the power transmitter and/or for adjusting anoperation point of the power transmitter, the difference between theactual operation point and the desired operation point may beadjusted/reduced. In case of minimizing this difference, an optimalpower reception may be performed.

The communication unit (890) and the control unit (810) may each beprovided as a separate device/chipset or may be collectively provided asone device/chipset.

FIG. 9 shows a communication frame structure according to an exemplaryembodiment of the present invention. This may correspond to acommunication frame structure in a shared mode.

Referring to FIG. 9, in the shared mode, different forms of frames maybe used along with one another. For example, in the shared mode, aslotted frame having a plurality of slots, as shown in (A), and a freeformat frame that does not have a specified format, as shown in (B), maybe used. More specifically, the slotted frame corresponds to a frame fortransmitting short data packets from the wireless power receiver (200)to the wireless power transmitter (100). And, since the free formatframe is not configured of a plurality of slots, the free format framemay correspond to a frame that is capable of performing transmission oflong data packets.

Meanwhile, the slotted frame and the free format frame may be referredto other diverse terms by anyone skilled in the art. For example, theslotted frame may be alternatively referred to as a channel frame, andthe free format frame may be alternatively referred to as a messageframe.

More specifically, the slotted frame may include a sync patternindicating the starting point (or beginning) of a slot, a measurementslot, nine slots, and additional sync patterns each having the same timeinterval that precedes each of the nine slots.

Herein, the additional sync pattern corresponds to a sync pattern thatis different from the sync pattern that indicates the starting point ofthe above-described frame. More specifically, the additional syncpattern does not indicate the starting point of the frame but mayindicate information related to the neighboring (or adjacent) slots(i.e., two consecutive slots positioned on both sides of the syncpattern).

Among the nine slots, each sync pattern may be positioned between twoconsecutive slots. In this case, the sync pattern may provideinformation related to the two consecutive slots.

Additionally, the nine slots and the sync patterns being provided beforeeach of the nine slots may have the same time interval. For example, thenine slots may have a time interval of 50 ms. And, the nine syncpatterns may have a time length of 50 ms.

Meanwhile, the free format frame, as shown in (B) may not have aspecific format apart from the sync pattern indicating the startingpoint of the frame and the measurement slot. More specifically, the freeformat frame is configured to perform a function that is different fromthat of the slotted frame. For example, the free format frame may beused to perform a function of performing communication of long datapackets (e.g., additional owner information packets) between thewireless power transmitter and the wireless power receiver, or, in caseof a wireless power transmitter being configured of multiple coils, toperform a function of selecting any one of the coils.

Hereinafter, a sync pattern that is included in each frame will bedescribed in more detail with reference to the accompanying drawings.

FIG. 10 is a structure of a sync pattern according to an exemplaryembodiment of the present invention.

Referring to FIG. 10, the sync pattern may be configured of a preamble,a start bit, a response field, a type field, an info field, and a paritybit. In FIG. 10, the start bit is illustrated as ZERO.

More specifically, the preamble is configured of consecutive bits, andall of the bits may be set to 0. In other words, the preamble maycorrespond to bits for matching a time length of the sync pattern.

The number of bits configuring the preamble may be subordinate to theoperation frequency so that the length of the sync pattern can be mostapproximate to 50 ms but within a range that does not exceed 50 ms. Forexample, in case the operation frequency corresponds to 100 kHz, thesync pattern may be configured of two preamble bits, and, in case theoperation frequency corresponds to 105 kHz, the sync pattern may beconfigured of three preamble bits.

The start bit may correspond to a bit that follows the preamble, and thestart bit may indicate ZERO. The ZERO may correspond to a bit thatindicates a type of the sync pattern. Herein, the type of sync patternsmay include a frame sync including information that is related to aframe, and a slot sync including information of the slot. Morespecifically, the sync pattern may be positioned between consecutiveframes and may correspond to a frame sync that indicate a start of theframe, or the sync pattern may be positioned between consecutive slotsamong a plurality of slots configuring the frame and may correspond to async slot including information related to the consecutive slots.

For example, in case the ZERO is equal to 0, this may indicate that thecorresponding slot is a slot sync that is positioned in-between slots.And, in case the ZERO is equal to 1, this may indicate that thecorresponding sync pattern is a frame sync being located in-betweenframes.

A parity bit corresponds to a last bit of the sync pattern, and theparity bit may indicate information on a number of bits configuring thedata fields (i.e., the response field, the type field, and the infofield) that are included in the sync pattern. For example, in case thenumber of bits configuring the data fields of the sync patterncorresponds to an even number, the parity bit may be set to when, and,otherwise (i.e., in case the number of bits corresponds to an oddnumber), the parity bit may be set to 0.

The response field may include response information of the wirelesspower transmitter for its communication with the wireless power receiverwithin a slot prior to the sync pattern. For example, in case acommunication between the wireless power transmitter and the wirelesspower receiver is not detected, the response field may have a value of‘00’. Additionally, if a communication error is detected in thecommunication between the wireless power transmitter and the wirelesspower receiver, the response field may have a value of ‘01’. Thecommunication error corresponds to a case where two or more wirelesspower receivers attempt to access one slot, thereby causing collision tooccur between the two or more wireless power receivers.

Additionally, the response field may include information indicatingwhether or not the data packet has been accurately received from thewireless power receiver. More specifically, in case the wireless powertransmitter has denied the data packet, the response field may have avalue of “10” (10—not acknowledge (NAK)). And, in case the wirelesspower transmitter has confirmed the data packet, the response field mayhave a value of “11” (11—acknowledge (ACK)).

The type field may indicate the type of the sync pattern. Morespecifically, in case the sync pattern corresponds to a first syncpattern of the frame (i.e., as the first sync pattern, in case the syncpattern is positioned before the measurement slot), the type field mayhave a value of ‘1’, which indicates a frame sync.

Additionally, in a slotted frame, in case the sync pattern does notcorrespond to the first sync pattern of the frame, the type field mayhave a value of ‘0’, which indicates a slot sync.

Moreover, the information field may determine the meaning of its valuein accordance with the sync pattern type, which is indicated in the typefield. For example, in case the type field is equal to 1 (i.e., in casethe sync pattern type indicates a frame sync), the meaning of theinformation field may indicate the frame type. More specifically, theinformation field may indicate whether the current frame corresponds toa slotted frame or a free-format frame. For example, in case theinformation field is given a value of ‘00’, this indicates that thecurrent frame corresponds to a slotted frame. And, in case theinformation field is given a value of ‘01’, this indicates that thecurrent frame corresponds to a free-format frame.

Conversely, in case the type field is equal to 0 (i.e., in case the syncpattern type indicates a slot sync), the information field may indicatea state of a next slot, which is positioned after the sync pattern. Morespecifically, in case the next slot corresponds to a slot that isallocated (or assigned) to a specific wireless power receiver, theinformation field is given a value of ‘00’. In case the next slotcorresponds to a slot that is locked, so as to be temporarily used bythe specific wireless power receiver, the information field is given avalue of ‘01’. Alternatively, in case the next slot corresponds to aslot that can be freely used by a random wireless power receiver, theinformation field is given a value of ‘10’.

FIG. 11 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an exemplaryembodiment of the present invention.

Referring to FIG. 11, the wireless power receiver operating in theshared mode may be operated in any one of a selection phase (1100), anintroduction phase (1110), a configuration phase (1120), a negotiationphase (1130), and a power transfer phase (1140).

Firstly, the wireless power transmitter according to the exemplaryembodiment of the present invention may transmit a wireless power signalin order to detect the wireless power receiver. More specifically, aprocess of detecting a wireless power receiver by using the wirelesspower signal may be referred to as an Analog ping.

Meanwhile, the wireless power receiver that has received the wirelesspower signal may enter the selection phase (1100). As described above,the wireless power receiver that has entered the selection phase (1100)may detect the presence or absence of an FSK signal within the wirelesspower signal.

In other words, the wireless power receiver may perform communication byusing any one of an exclusive mode and a shared mode in accordance withthe presence or absence of the FSK signal.

More specifically, in case the FSK signal is included in the wirelesspower signal, the wireless power receiver may operate in the sharedmode, and, otherwise, the wireless power receiver may operate in theexclusive mode.

In case the wireless power receiver operates in the shared mode, thewireless power receiver may enter the introduction phase (1110). In theintroduction phase (1110), the wireless power receiver may transmit acontrol information (CI) packet to the wireless power transmitter inorder to transmit the control information packet during theconfiguration phase, the negotiation phase, and the power transferphase. The control information packet may have a header and informationrelated to control. For example, in the control information packet, theheader may correspond to 0X53.

In the introduction phase (1110), the wireless power receiver performsan attempt to request a free slot for transmitting the controlinformation (CI) packet during the following configuration phase,negotiation phase, and power transfer phase. At this point, the wirelesspower receiver selects a free slot and transmits an initial CI packet.If the wireless power transmitter transmits an ACK as a response to thecorresponding CI packet, the wireless power transmitter enters theconfiguration phase. If the wireless power transmitter transmits a NACKas a response to the corresponding CI packet, this indicates thatanother wireless power receiver is performing communication through theconfiguration and negotiation phase. In this case, the wireless powerreceiver re-attempts to perform a request for a free slot.

If the wireless power receiver receives an ACK as a response to the CIpacket, the wireless power receiver may determine the position of aprivate slot within the frame by counting the remaining sync slots up tothe initial frame sync. In all of the subsequent slot-based frames, thewireless power receiver transmits the CI packet through thecorresponding slot.

If the wireless power transmitter authorizes the entry of the wirelesspower receiver to the configuration phase, the wireless powertransmitter provides a locked slot series for the exclusive usage of thewireless power receiver. This may ensure the wireless power receiver toproceed to the configuration phase without any collision.

The wireless power receiver transmits sequences of data packets, such astwo identification data packets (IDHI and IDLO), by using the lockedslots. When this phase is completed, the wireless power receiver entersthe negotiation phase. During the negotiation state, the wireless powertransmitter continues to provide the locked slots for the exclusiveusage of the wireless power receiver. This may ensure the wireless powerreceiver to proceed to the negotiation phase without any collision.

The wireless power receiver transmits one or more negotiation datapackets by using the corresponding locked slot, and the transmittednegotiation data packet(s) may be mixed with the private data packets.Eventually, the corresponding sequence is ended (or completed) alongwith a specific request (SRQ) packet. When the corresponding sequence iscompleted, the wireless power receiver enters the power transfer phase,and the wireless power transmitter stops the provision of the lockedslots.

In the power transfer phase, the wireless power receiver performs thetransmission of a CI packet by using the allocated slots and thenreceives the power. The wireless power receiver may include a regulatorcircuit. The regulator circuit may be included in acommunication/control unit. The wireless power receiver mayself-regulate a reflected impedance of the wireless power receiverthrough the regulator circuit. In other words, the wireless powerreceiver may adjust the impedance that is being reflected for an amountof power that is requested by an external load. This may prevent anexcessive reception of power and overheating.

In the shared mode, (depending upon the operation mode) since thewireless power transmitter may not perform the adjustment of power as aresponse to the received CI packet, in this case, control may be neededin order to prevent an overvoltage state.

Hereinafter, it is described a method and wireless power transmissionapparatus for performing communication for power management andauthentication with the status and authority as a master/transmitterdepending on a situation.

1. Definition and Usage of Power Indicator

FIG. 12 illustrates an available power indicator according to anexample.

Referring to FIG. 12, an available power indicator according to anembodiment may mean a power that a wireless power transmission apparatusmay provide or transmit to a wireless power reception apparatus as anoutput in a power transfer phase, and particularly, the available powerindicator may include potential power (PP), guaranteed power (GP) andtarget power (TP).

The potential power may mean output power or an amount of output powerof the reference wireless power reception apparatus that the wirelesspower transmission apparatus is available to make during a powertransfer phase. The potential power may be fixed by a design.

The guaranteed power may mean output power or an amount of output powerof the reference wireless power reception apparatus that the wirelesspower transmission apparatus is available to ensure in any time during apower transfer phase. The guaranteed power is negotiated before thepower transfer phase but may be maintained fixedly during the powertransfer phase. The guaranteed power may be at least 5 W.

The target power may mean output power or an amount of output power ofthe reference wireless power reception apparatus that the wireless powertransmission apparatus provides during a power transfer phase. Thetarget power may be dynamic and changed during the power transfer phase.The supported target power may depend on a condition that the wirelesspower transmission apparatus operates.

FIG. 13 illustrates a method of each available power indicator being setin a negotiation phase according to an example.

Referring to FIG. 13, the wireless power transmission apparatus reservesan enough margin between the potential power and the guaranteed power.The wireless power transmission apparatus negotiates the guaranteedpower for expected operation conditions during the power transfer phase.For example, depending on a design and a market of the wireless powertransmission apparatus, the wireless power transmission apparatus may beconfigured to negotiate the guaranteed power in a level of 50% of thepotential power. Such a negotiation of the guaranteed power may beperformed by the communication/control unit 120 of FIG. 4 or the controlunit 710 of FIG. 7.

The wireless power transmission apparatus may set the negotiatedguaranteed power to an initial target power. The target power may beupdated according to an actual power (supported by the wireless powertransmission apparatus in a peripheral condition on charging currently)pulled by the wireless power reception apparatus. Meanwhile, the initialtarget power may also be set by the other method as shown in FIG. 14.Setting of the initial target power may be performed by thecommunication/control unit 120 of FIG. 4 or the control unit 710 of FIG.7.

FIG. 14 illustrates a method of each available power indicator being setin a negotiation phase according to another example.

Referring to FIG. 14, the wireless power transmission apparatus may setthe potential power to an initial target power. The target power may beupdated according to an actual condition. Setting of the initial targetpower may be performed by the communication/control unit 120 of FIG. 4or the control unit 710 of FIG. 7.

In the power transfer phase, the wireless power transmission apparatusand the wireless power reception apparatus may perform a power controlbased on an available power indicator or adjust the available powerindicator if it is required. Hereinafter, the power control or theadjustment of the available power indicator may be performed by thecommunication/control unit 120 of FIG. 4 or the control unit 710 of FIG.7.

For example, the wireless power transmission apparatus may take over acontrol authority of a level over the guaranteed power. If a conditionis permitted, the wireless power transmission apparatus may adapt thepower level according to the existing control error and may update thetarget power to a received power of the wireless power receptionapparatus.

As an aspect, the wireless power transmission apparatus may adjust thetarget power by reporting a request for communication (RFC) for acommunication. The RFC may be substituted by a term such as request forrenegotiation (RFR), request for auxiliary transport (RFA), attention,or the like, and even in the case that the term is different, thefunction related to the available power indicator or the functionrelated to a wireless power transmission apparatus (PTx)-initiatedcommunication may be the same or similar. The wireless powertransmission apparatus may want to decrease the target power based on anambient charging condition which is deteriorated. Alternatively, thewireless power transmission apparatus may want to increase the targetpower based on an ambient charging condition which is improved. Duringsuch a re-negotiation phase, the wireless power reception apparatus mayacknowledge the target power of the wireless power transmissionapparatus and adjust an operation mode if it is required.

In another aspect, in the case that a condition is changed during thepower transfer phase, the wireless power transmission apparatus mayadapt to the target power accordingly. In the case that the target poweris changed, the wireless power transmission apparatus may send an alertto the wireless power reception apparatus. This is a selective functionfor the wireless power reception apparatus but may be an indispensablefunction for the wireless power transmission apparatus. In addition, thewireless power reception apparatus may request to apply an alert duringthe negotiation phase to the wireless power transmission apparatus. Inthe case that an actual power is greater than the target power, thewireless power transmission apparatus may reduce or restrict an actualpower transfer. The wireless power transmission apparatus may not reducean actual power transfer abruptly without a warning or an alert. Theoperation of transmitting the alert may be performed by acommunication/control unit 120 of FIG. 4 or a control unit 710 of FIG.7.

For another example, the wireless power transmission apparatus mayreport ‘NAK’ when unable to maintain the guaranteed power in response tothe received power (RP) packet (RPP). This is an exceptional case, andfor example, this may include the case that it is in very bad couplingenvironment, a state of high temperature or a foreign substance isinserted. The NAK report may be performed by the communication/controlunit 120 of FIG. 4 or the control unit 710 of FIG. 7. At this time, thewireless power reception apparatus may transmit an end power transfer(EPT) packet, and the value may be 0x08. A transmission of the EPTpacket may be performed by the communication/control unit 120 of FIG. 4or the control unit 710 of FIG. 7.

In this case, the wireless power transmission apparatus restarts thepower transmission to perform a detection of foreign substances beforethe restarting.

As another example, the wireless power reception apparatus may treat theguaranteed power. A load may be provided such that a rectified voltageis high enough in the guaranteed power. In the case that the requestedpower is equal to or greater than the guaranteed power and the wirelesspower transmission apparatus disregards a positive control error, thewireless power transmission apparatus may perform a power transmissioncontinuously, and in this case, the EPT packet (0x08) is not required.

FIG. 15 is a diagram illustrating a procedure in which a power controlis performed based on each available power indicator in a power transferphase according to an example.

Referring to FIG. 15, the wireless power transmission apparatus maychange (increase or decrease) the target power according to a currentambient charging condition during the power transfer phase and therenegotiation phase. That is, the target power may be changed throughthe renegotiation phase, and during the renegotiation phase, the powertransfer is continued in a previous power level. Such a change of thetarget power may be performed by the communication/control unit 120 ofFIG. 4 or the control unit 710 of FIG. 7.

FIG. 16 is a diagram illustrating a procedure in which a power controlis performed based on each available power indicator in a power transferphase according to an example.

Referring to FIG. 16, the wireless power transmission apparatus maychange (increase or decrease) the available power indicator (i.e.,target power) according to a current ambient charging condition duringthe power transfer.

Based on the communication initiated by the wireless power transmissionapparatus, it is described an embodiment that the wireless powertransmission apparatus and the wireless power reception apparatus changethe available power indicator as below.

The change of the available power indicator according to a firstembodiment may include performing, by the wireless power transmissionapparatus, an alert for changing of a first available power indicatorpreviously negotiated by transmitting “request for communication (RFC)”to the wireless power reception apparatus in response to RP or CEpacket, transmitting, by the wireless power reception apparatus, aresponse signal indicating being ready to receive a communication of thewireless power transmission apparatus to the wireless power transmissionapparatus, transmitting, by the wireless power transmission apparatus, apacket related to a second available power indicator to the wirelesspower reception apparatus, and transmitting, by the wireless powerreception apparatus, ACK to the wireless power transmission apparatus byadjusting an operation mode according to the second available powerindicator. The response signal indicating being ready to receive acommunication may be poll or ACK packet. In addition, the secondavailable power indicator may include at least one of the potentialpower, the guaranteed power and the target power.

As an example, in the case that the second available power indicator isthe guaranteed power, the wireless power transmission apparatus maytransmit a packet related to the guaranteed power to the wireless powerreception apparatus after receiving the response signal from thewireless power reception apparatus, and the wireless power receptionapparatus may adjust an operation mode according to the guaranteedpower. The packet related to the guaranteed power may include acapability packet of the wireless power transmission apparatusindicating a guaranteed power value as shown in FIG. 19.

As another example, in the case that the second available powerindicator is the target power, the wireless power transmission apparatusmay transmit a packet related to the target power to the wireless powerreception apparatus after receiving the response signal from thewireless power reception apparatus, and the wireless power receptionapparatus may adjust an operation mode according to the target power.The packet related to the target power may include a packet indicating atarget power value as shown in FIG. 19 or FIG. 20.

Meanwhile, since the RFC may be related to the renegotiation request(RFR), a change of the available power indicator according to a secondembodiment may further include changing a power contract according tothe available power indicator by entering the renegotiation phase afterthe wireless power reception apparatus that receives the RFC in thefirst embodiment transmits ACK.

The transmission of the RFC, the target power packet and the receptionof the response signal may be performed by the communication/controlunit 120 of FIG. 4 or the control unit 710 of FIG. 7. The transmissionof the response signal may be performed by the communication/controlunit 220 of FIG. 4 or the communication unit 890 of FIG. 8. Theadjustment of the operation mode according to the target power may beperformed by the communication/control unit 220 of FIG. 4 or the controlunit 810 of FIG. 8.

2. Signal or Packets of the Wireless Power Transmission Apparatus Usedin Relation to the Available Power Indicator

(1) Bit Pattern Response

In relation to the available power indicator, the wireless powertransmission apparatus may transmit a bit pattern response to thewireless power reception apparatus. The bit pattern response istransmitted in response to a type of communication packet (e.g., RPpacket) that the wireless power reception apparatus transmits to thewireless power transmission apparatus. A generation and a transmissionof the bit pattern response may be performed by thecommunication/control unit 120 of FIG. 4 or the control unit 710 of FIG.7.

As an example, the bit pattern response may include ACK, NAK, ND andRFR. For example, the RFR is 8 bits and the value may be set to“00110011”b. Meanwhile, the remaining bit pattern responses may alsohave a value of ACK(‘111111’b), NAK(‘0000000’b) and ND(‘01010101’b). Inthis case, it is identified that bit patterns are clearly distinguishedbetween different bit pattern responses.

The wireless power transmission apparatus may request the wireless powerreception apparatus to enter the renegotiation phase by transmitting bitpattern response RFR to the wireless power reception apparatus to updatethe target power. The update of the target power is objected to increaseor decrease the required power by reflecting a current ambient chargingcondition. The protocol related to a transmission procedure of the RFRis as shown in FIG. 17.

FIG. 17 illustrates a protocol related to a transmission procedure ofthe RFR according to an embodiment.

Referring to FIG. 17, the wireless power transmission apparatustransmits an RFR 1705, which is a bit pattern response, after an RPP1700 to request the wireless power reception apparatus to enter therenegotiation phase. The transmission of the RFR may be performed by thecommunication/control unit 120 of FIG. 4 or the communication unit 790of FIG. 7. Accordingly, the wireless power reception apparatus transmitsa renegotiation (RNG) packet 1710 to the wireless power transmissionapparatus, and the wireless power transmission apparatus transmits anACK 1715 to the wireless power reception apparatus. The transmission ofthe renegotiation packet may be performed by the communication/controlunit 220 of FIG. 4 or the communication unit 890 of FIG. 8. The responseof the wireless power transmission apparatus may be available not onlyfor the RPP, but the exiting ‘NAK’ may be reused for the RFR by defininga new response of the wireless power transmission apparatus for a CEpacket.

As another example, the bit pattern response may include ACK, NAK, NDand RFC. For example, the RFC is 8 bits and the value may be set to“00110011”b. Meanwhile, the remaining bit pattern responses may alsohave a value of ACK(‘11111’b), NAK(‘0000000’b) and ND(‘01010101’b). Inthis case, it is identified that bit patterns are clearly distinguishedbetween different bit pattern responses. That is, since the bit patternresponses are defined as repetitive bit patterns, quick recognition andredundancy and simple implementation become available. For example, 4bits received by the wireless power reception apparatus exactly matchesone of predefined bit patterns, the wireless power reception apparatusmay be convinced of the meaning of the bit pattern response afterreceiving first 4 bits (or on the timing). The wireless power receptionapparatus may miss a part of bits but identify a pattern and may correcta flipping bit.

The transmission procedure of the RFC includes sending, by the wirelesspower transmission apparatus, an alert to the wireless power receptionapparatus in response to the RP packet or the CE packet when requiring amatter to communicate, transmitting, by the wireless power receptionapparatus, ACK when the wireless power reception apparatus is in acondition to hear the wireless power transmission apparatus, responding,by the wireless power transmission apparatus, with information relatedto the target power actually supported, and transmitting, by thewireless power reception apparatus, ACK after being accommodated with anew situation of a new target power. Here, the message of the wirelesspower transmission apparatus and the response and operation of thewireless power reception apparatus are defined according to the messageof the wireless power transmission apparatus. For example, with respectto the information related to the target power, the wireless powerreception apparatus transmits the ACK after adjusting the operationmode.

As still another example, the bit pattern response may include ACK, NAK,ND and request for auxiliary transport (RFA). For example, the RFA is 8bits and the value may be set to “00110011”b. Meanwhile, the remainingbit pattern responses may also have a value of ACK(‘111111’b),NAK(‘0000000’b) and ND(‘01010101’b). In this case, it is identified thatbit patterns are clearly distinguished between different bit patternresponses.

The transmission procedure of the RFA includes sending, by the wirelesspower transmission apparatus, an alert to the wireless power receptionapparatus in response to the RP packet when requiring a matter tocommunicate, transmitting, by the wireless power reception apparatus,ACK when the wireless power reception apparatus is in a condition tohear the wireless power transmission apparatus, responding, by thewireless power transmission apparatus, with information related to thetarget power actually supported, and transmitting, by the wireless powerreception apparatus, ACK after being accommodated with a new situationof a new target power. For the compatibility with the legacy Qi wirelesspower reception apparatus, the wireless power reception apparatus maytransmit the RFA only in response to the RP packet in mode 0.

(2) RFA Packet of the Wireless Power Transmission Apparatus

The RFA may be defined by an RFA packet which is indicated by a headerfor the RFA as shown in FIG. 18. For example, when a request field isset to ‘11111111’b, the RFA indicates a request of the wireless powertransmission apparatus for an auxiliary data transport. Here, anauxiliary transport includes a data transport and the auxiliary datatransport. The header for data transmission indicates a type of datapacket. The header for auxiliary data transport indicates that thecorresponding packet is auxiliary data which may be interpreted by ahigher layer application.

(3) Capability Packet of the Wireless Power Transmission Apparatus

The available power indicator may be transmitted with being included ina capability packet of the wireless power transmission apparatus. Atransmission of the available power indicator and a transmission of thecapability packet may be performed by the communication/control unit 120of FIG. 4 or the communication unit 790 of FIG. 7.

FIG. 19 illustrates a structure of the capability packet of the wirelesspower transmission apparatus including an available power indicatoraccording to an embodiment.

Referring to FIG. 19, the capability packet is 3 bytes, and the firstbyte B0 includes a power class and a (target) guaranteed power value,and the second byte B1 includes a reserved and a potential power value,and includes a reserved, WPID and Not Res Sens.

In the negotiation phase, the (target) guaranteed power value mayindicate an output power or an amount of output power of a referencewireless power reception apparatus that the wireless power transmissionapparatus ensures a possibility in any times during the power transferphase.

In the renegotiation phase, the (target) guaranteed power value may meanan output power or an amount of output power of the wireless powerreception apparatus that the wireless power transmission apparatus wantsrenegotiation under a current ambient condition.

(4) Target Power Packet of the Wireless Power Transmission Apparatus

The target power value may be transmitted with being included in thetarget power packet of the wireless power transmission apparatus. Atransmission of the target power packet may be performed by thecommunication/control unit 120 of FIG. 4 or the communication unit 790of FIG. 7.

FIG. 20 illustrates a structure of the target power packet of thewireless power transmission apparatus according to an embodiment.

Referring to FIG. 20, the target power packet is 1 byte, and a partthereof may be reserved bit and the remaining part thereof may be afield indicating a target power value. For example, the reserved bit maybe 2 bits and the field indicating a target power value may be 6 bits.The target power value may mean an output power or an amount of outputpower of the wireless power reception apparatus that the wireless powertransmission apparatus provides during the power transfer phase. Thetarget power value is dynamic and may be changed during the powertransfer phase. The supported target power may be dependent upon thecondition that the wireless power transmission apparatus operates.

(5) General Request Packet (GRP) and Specific Request Packet (SRP)

The wireless power reception apparatus may use a general request packetor a specific request packet for obtaining a value of a currentlyavailable guaranteed power (or target power). A generation and atransmission of the general or specific request packet may be performedby the communication/control unit 220 of FIG. 4 or the communicationunit 890 of FIG. 8.

As an example, the wireless power reception apparatus may read thecapability packet of the wireless power transmission apparatus by usingthe general request packet. Here, the target power value may be the sameas the guaranteed power value which is included in the capabilitypacket. Alternatively, the wireless power reception apparatus may usethe general request packet for obtaining information for the targetpower which is supported.

As another example, the wireless power reception apparatus may read thetarget power value (or guaranteed power value) of the wireless powertransmission apparatus. The specific request packet is used forobtaining an answer of yes/no, and with respect to the available powerindicator, may be used for requesting such that the target power is notabruptly decreased but uniformly maintained.

(6) Response Packet of the Wireless Power Reception Apparatus

With respect to the available power indicator, a response packet of thewireless power reception apparatus may be used. A generation and atransmission of the response packet of the wireless power receptionapparatus may be performed by the communication/control unit 220 of FIG.4 or the communication unit 890 of FIG. 8.

FIG. 21 illustrates a structure of the response packet of the wirelesspower reception apparatus according to an embodiment.

Referring to FIG. 21, the response packet is 1 byte, and the whole 8bits may be a response field indicating a multiple response.

As an example, when the response field is set to ‘11111111’b, theresponse packet may indicate ACK, when the response field is set to‘00000000’b, the response packet may indicate NAK, and when the responsefield is set to ‘01010101’b, the response packet may indicate ND.

As another example, when the response field is set to ‘111111’b, theresponse packet may indicate ACK, when the response field is set to‘00000000’b, the response packet may indicate NAK, when the responsefield is set to ‘01010101’b, the response packet may indicate ND, andwhen the response field is set to ‘00110011’b, the response packet mayindicate RFA.

(7) Response Packet of the Wireless Power Transmission Apparatus

With respect to the available power indicator, a response packet of thewireless power transmission apparatus may be used. A generation and atransmission of the response packet of the wireless power transmissionapparatus may be performed by the communication/control unit 120 of FIG.4 or the communication unit 790 of FIG. 7. FIG. 22 illustrates astructure of the response packet of the wireless power transmissionapparatus according to an embodiment.

Referring to FIG. 22, the response packet is 1 byte, and the whole 8bits may be a response field indicating a multiple response. This is thesame structure as the response packet of the wireless power receptionapparatus.

As an example, when the response field is set to ‘11111111’b, theresponse packet may indicate ACK, when the response field is set to‘00000000’b, the response packet may indicate NAK, when the responsefield is set to ‘01010101’b, the response packet may indicate ND, andwhen the response field is set to ‘00110011’b, the response packet mayindicate RFA.

3. Communication Method Initiated by the Wireless Power TransmissionApparatus (PTx-Initiated) Related to the Available Power Indicator

A communication initiated by the wireless power transmission apparatusmay be used the functions of authentication and power management. In theauthentication initiated by the wireless power transmission apparatus,the wireless power transmission apparatus is required to start theauthentication as an initiator by transmitting data stream of a requestmessage on the timing requested to the wireless power transmissionapparatus itself.

In the power management initiated by the wireless power transmissionapparatus, the wireless power transmission apparatus is required torenegotiate a power level dependent upon a charging environment on thetiming requested to the wireless power transmission apparatus itself.

Accordingly, the communication initiated by the wireless powertransmission apparatus needs to provide a means for requesting anattention from the wireless power reception apparatus. That is, when thewireless power transmission apparatus is intended to transmit data tothe wireless power reception apparatus, the above-described bit patternresponse (i.e., RFR, RFC and RFA) may be used. Through the bit patternresponse, an opportunity is given to transmit data to the wireless powertransmission apparatus. However, even in this case, the wireless powerreception apparatus may allow/disallow the request of the wireless powertransmission apparatus and may keep a control of the communication.

In order for the wireless power transmission apparatus to transmit data,a protocol therefor needs to be defined. For example, in thecommunication initiated by the wireless power transmission apparatus,for data transmission, an auxiliary transport or an auxiliary datatransport protocol may be used.

FIG. 23 is a flowchart for the wireless power transmission apparatus totransmit information related to the available power indicator based onthe auxiliary transport protocol according to an embodiment.

Referring to FIG. 23, the auxiliary transport protocol may bedistinguished by step (steps S2300 and S2305) of requesting, by thewireless power transmission apparatus, an auxiliary transport and step(steps S2310 and S2315) of performing the auxiliary transport by theauxiliary transport request, largely.

First, in the step of requesting the auxiliary transport, the wirelesspower reception apparatus transmits an RP packet (RPP) to the wirelesspower transmission apparatus (step, S2300). A generation and atransmission of the RP packet may be performed by thecommunication/control unit 220 of FIG. 4 or the communication unit 890of FIG. 8. The wireless power transmission apparatus transmits the RFAto the wireless power reception apparatus (step, S2305). A generationand a transmission of the RFA packet may be performed by thecommunication/control unit 120 of FIG. 4 or the communication unit 790of FIG. 7. The RFA may be the bit pattern response or the RFA packet.The purpose of the wireless power transmission apparatus to transmit theRFA may be to transmit data of the wireless power transmission apparatusto the wireless power reception apparatus by using the communicationinitiated by the wireless power transmission apparatus. At this time,the data that the wireless power transmission apparatus is intended totransmit may include a packet related to the available power indicator.For example, the packet related to the available power indicator may beinformation related to at least one of the target power, the guaranteedpower and the potential power. In this case, the purpose of the wirelesspower transmission apparatus to transmit the RFA may be to request arenegotiation for changing the available power indicator (e.g., increaseor decrease of the guaranteed power).

Next, in the step of performing the auxiliary transport, the wirelesspower reception apparatus that receives the RFA transmits a responsepacket for the RFA to the wireless power transmission apparatus (step,S2310). A generation and a transmission of the response packet to theRFA may be performed by the communication/control unit 220 of FIG. 4 orthe communication unit 890 of FIG. 8. As an example, the response packetfor the RFA may be ACK packet indicating that the wireless powerreception apparatus identifies a request of the wireless powertransmission apparatus. As another example, the response packet for theRFA may indicate that the wireless power reception apparatus is in thestate of hearing the wireless power transmission apparatus.

Later, the wireless power transmission apparatus transmits a packet forthe available power indicator to the wireless power reception apparatus(step, S2315). A generation and a transmission of the packet for theavailable power indicator may be performed by the communication/controlunit 120 of FIG. 4 or the communication unit 790 of FIG. 7.

FIG. 24a illustrates an ATX (or ATD) step performing the auxiliarytransport in detail according to an embodiment.

Referring to FIG. 24a , in the ATX (or ATD) step (S2400) that performsthe auxiliary transport, two steps are paired, which include a step(ATX_PRx; S2405) of performing the auxiliary transport by the wirelesspower reception apparatus and a step (ATX_PTx; S2410) of performing theauxiliary transport by the wireless power transmission apparatus. In theATX_PRx, it is transmitted auxiliary data or an auxiliary data packet,or a response (ACK/NAK/RFA) packet of the wireless power receptionapparatus. A generation and a transmission of the auxiliary data or theauxiliary data packet, or the response (ACK/NAK/RFA) packet of thewireless power reception apparatus may be performed by thecommunication/control unit 220 of FIG. 4 or the communication unit 890of FIG. 8.

In the ATX_PTx, it is transmitted auxiliary data or an auxiliary datapacket, a response (ACK/NAK/RFA) packet, or a bit pattern response ofthe wireless power transmission apparatus. The ATX may be called asauxiliary data transport (ADT) or auxiliary data control transport(ADC). A generation and a transmission of the auxiliary data packet, theresponse (ACK/NAK/RFA) packet, or the bit pattern response of thewireless power transmission apparatus may be performed by thecommunication/control unit 120 of FIG. 4 or the communication unit 790of FIG. 7.

FIG. 24b illustrates an ATX (or ATD) step performing the auxiliarytransport in detail according to another embodiment.

Referring to FIG. 24b , in the ATX (or ATD) step (S2420) that performsthe auxiliary transport, two steps are paired, which include a step(S2525) of performing the auxiliary transport by the wireless powertransmission apparatus (or wireless power reception apparatus) and astep (S2530) of transmitting ACK/NAK or a bit pattern response by thewireless power reception apparatus (wireless power transmissionapparatus). A header of the ADT packet may indicate header A or headerB. The ADT may be transmitted in a period of 500 ms, for example, in thecase that the CE value is 0 or close to 0). Alternatively, in the casethat the CE value is a predetermined value or more, the ADT transmissionmay be omitted. A single ADT (ADT data pair) may be transmitted betweentwo adjacent CE packets.

FIG. 25 is a flowchart for the wireless power transmission apparatus totransmit information related to the available power indicator based onthe auxiliary transport protocol according to another embodiment.

Referring to FIG. 25, the wireless power reception apparatus transmits aCE packet and an RP packet to the wireless power transmission apparatus(step, S2500). A generation and a transmission of the CE packet and theRP packet may be performed by the communication/control unit 220 of FIG.4 or the communication unit 890 of FIG. 8. The wireless powertransmission apparatus transmits a bit pattern response RFC to thewireless power reception apparatus (step, S2505). Accordingly, thewireless power transmission apparatus gets an attention of the wirelesspower reception apparatus and requests a communication start by thewireless power transmission apparatus. In this embodiment, it is assumedthat the wireless power transmission apparatus transmits the bit patternresponse RFC for the purpose of changing the available power indicator.In this case, the wireless power transmission apparatus performs achanging procedure of the available power indicator in the renegotiationphase. Depending on an embodiment, the RFC may be replaced by RFA, RFRor ATN.

Meanwhile, the wireless power reception apparatus inquires the reason ofstarting communication by the wireless power transmission apparatus bytransmitting a response packet (general request (GR) packet) for the RFCto the wireless power transmission apparatus (step, S2510). This is alsocalled a poll. A generation and a transmission of the response packetmay be performed by the communication/control unit 220 of FIG. 4 or thecommunication unit 890 of FIG. 8.

As an example, GR packet may be used as the response packet, and the GRpacket may have the structure shown in FIG. 26, for example. Referringto FIG. 26, the GR packet includes a request field. The wireless powerreception apparatus transmits the GR packet including a request fieldindicating a reason for attention (RA) to the wireless powertransmission apparatus and polls the reason of attention request. Therequest field may be a header of the RA packet.

Referring to FIG. 25 again, the wireless power transmission apparatusinforms that renegotiation is required to the wireless power receptionapparatus by reason of a change of the available power indicator (step,S2515). For step S2515, a separate RA packet may be used. Here, the RApacket may have a structure shown in FIG. 27. Referring to FIG. 27, theRA packet is 1 byte and may indicate a reason for an attention request,and for example, when b0=1, the RA packet may indicate renegotiation,and when b1=1, the RA packet may indicate ADT data stream (e.g.,authentication) transmission. In addition, b2 to b7 may be reservedbits. The RA may also be called a reason for request (RR). A generationand a transmission of the RA packet may be performed by thecommunication/control unit 120 of FIG. 4 or the communication unit 790of FIG. 7.

Referring to FIG. 25 again, the wireless power reception apparatusdetermines whether to accept the renegotiation request and transmits ACKpacket as shown in FIG. 28 as a sign of accept (step, S2520), andtransmits CE packet for a progressing power transfer to the wirelesspower transmission apparatus (step, S2525). The ACK/NAK packet is 1-byteinformation, and when the value indicates ‘11111111’b, it is indicatedACK (RA packet or ADT data packet is received without any problem, andwhen the value indicates ‘00000000’b, it is indicated NAK (an erroroccurs when receiving RA packet or ADT data packet).

Later, the wireless power reception apparatus transmits a renegotiationpacket to the wireless power transmission apparatus (step, S2530). Inresponse to it, the wireless power transmission apparatus responds withACK (step, S2535), and the wireless power reception apparatus transmitsa specific request packet to the wireless power transmission apparatusto receive a required packet (step, S2540). Later, the wireless powertransmission and reception apparatuses enter the renegotiation phase andchange the available power indicator after changing required packets.

Meanwhile, the communication initiated by the wireless powertransmission apparatus may also be performed in a way that the wirelesspower reception apparatus inquires whether there is data stream to sendto the wireless power transmission apparatus.

For this, the wireless power reception apparatus may transmit ADT datapacket including a start of data stream (SOD) or an end of data stream(EOD). For example, in a start of the ADT data stream, the start of datastream (SOD) packet may be added. Alternatively, in an end of the datastream, the EOD packet may be added. The structure of the SOD/EOD packetmay be as shown in FIG. 29, for example. A generation and a transmissionof the ADT data packet including the SOD or the EOD may be performed bythe communication/control unit 220 of FIG. 4 or the communication unit890 of FIG. 8.

FIG. 30 illustrates an ADT data transmission procedure according to anembodiment. This is the procedure that the wireless power receptionapparatus transmits the ADT data to the wireless power transmissionapparatus by using ADT transport protocol.

Referring to FIG. 30, in the power transfer phase, the wireless powerreception apparatus transmits CE packet to the wireless powertransmission apparatus, and subsequently, transmits SOD to the wirelesspower transmission apparatus (step, S3000). When the wireless powertransmission apparatus receives it successfully, in response to it, thewireless power reception apparatus transmits ACK which is a bit patternresponse (step, S3005). The wireless power reception apparatus performsa role of master that transmits a message to the wireless powertransmission apparatus.

The wireless power reception apparatus transmits a 0^(th) ADT datapacket ADT_PRx(0) successfully (step, S3010), and then, receives ACK(step, S3015). The process of transmitting the ADT data packet may beincluded in the power transfer phase, and in this case, the CE packetmay be transmitted from the wireless power reception apparatus to thewireless power transmission apparatus in the middle of the ADT datapacket or periodically.

Meanwhile, when the wireless power transmission apparatus fails toreceive a first ADT data packet ADT_PRx(1) (step, S3020), the wirelesspower transmission apparatus transmits NAK to the wireless powerreception apparatus (step, S3025). Later, the wireless power receptionapparatus retransmits the first ADT data packet ADT_PRx(1) (step,S3030). After repeating the ADT packet transmission sequence, thewireless power reception apparatus transmits the lastly remaining 5^(th)ADT data packet ADT_PRx(5) successfully, and then receives NAK. Inresponse to it, the wireless power reception apparatus transmits the EODsuccessfully (step, S3035) and receives ACK, and accordingly, terminatesthe transport procedure of the ADT data.

In the method and the wireless power transmission apparatus or themethod and the wireless power reception apparatus according to theembodiments of the present invention, since not all elements or stepsare essential, the method and the wireless power transmission apparatusor the method and the wireless power reception apparatus may perform apart or the whole of the elements or steps described above. In addition,the embodiments of the method and the wireless power transmissionapparatus or the method and the wireless power reception apparatus maybe performed in combination. Furthermore, the elements and the steps arenot necessarily performed in the order as described above, but it isalso available that the step described later may be performed first.

The description so far is just an exemplary description of the technicalconcept of the present invention, and various modification andalteration are available by those skilled in the art without departingfrom the substantial characteristics of the present invention.Accordingly, the embodiments described above may be implementedseparately or in combination.

Therefore, the embodiments described in the present invention is not tolimit the technical concept of the present invention but to describe,and the scope of the technical concept of the present invention is notlimited by the embodiments. It is interpreted that the scope of thepresent invention should be interpreted by the claims below and all ofthe equivalent technical concepts are included in the scope of thepresent invention.

What is claimed is:
 1. A wireless power transmitter comprising: a powerconversion unit configured to transfer wireless power to a wirelesspower receiver by forming magnetic coupling with the wireless powerreceiver; and a communication/control unit configured to communicatewith the wireless power receiver to control transmission of the wirelesspower and to perform transmission or reception of data, wherein thecommunication/control unit further configured to: set a target powerlevel based on a charging condition, receive, from the wireless powerreceiver, a received power packet (RPP) which indicates a value of thewireless power received by the wireless power receiver, transmit a bitpattern to the wireless power receiver in response to the RPP, the bitpattern being used to request communication initiated by the wirelesspower transmitter, receive, from the wireless power receiver, a responsepacket to allow the communication initiated by the wireless powertransmitter, transmit, to the wireless power receiver, informationindicating the target power level in response to the response packet,negotiate a guaranteed power level adjusted by the wireless powerreceiver such that the target power level is kept equal to or largerthan the guaranteed power level.
 2. The wireless power transmitter ofclaim 1, wherein the target power level is kept equal to or lower than apotential power level which is the highest power provided by thewireless power transmitter.
 3. The wireless power transmitter of claim1, wherein the guaranteed power level is adjusted by the wireless powerreceiver based on the target power level.
 4. The wireless powertransmitter of claim 1, wherein the information indicating the targetpower level is 6 bits.
 5. The wireless power transmitter of claim 1,wherein setting a target power level based on a charging conditionincludes increasing or decreasing the target power level based on thecharging condition.
 6. A method of data transmission performed by awireless power transmitter, the method comprising: transferring wirelesspower to a wireless power receiver by using magnetic coupling betweenthe wireless power transmitter and the wireless power receiver; settinga target power level based on a charging condition; receiving, from thewireless power receiver, a received power packet (RPP) which indicates avalue of the wireless power received by the wireless power receiver;transmitting a bit pattern to the wireless power receiver in response tothe RPP, the bit pattern being used to request communication initiatedby the wireless power transmitter; receiving, from the wireless powerreceiver, a response packet to allow the communication initiated by thewireless power transmitter; transmitting, to the wireless powerreceiver, information indicating the target power level in response tothe response packet; and negotiating a guaranteed power level adjustedby the wireless power receiver such that the target power level is keptequal to or larger than the guaranteed power level.
 7. The method ofclaim 6, wherein the target power level is kept equal to or lower than apotential power level which is the highest power provided by thewireless power transmitter.
 8. The method of claim 6, wherein theguaranteed power level is adjusted by the wireless power receiver basedon the target power level.
 9. The method of claim 6, wherein theinformation indicating the target power level is 6 bits.
 10. The methodof claim 6, wherein setting a target power level based on a chargingcondition includes increasing or decreasing the target power level basedon the charging condition.
 11. A wireless power receiver comprising: apower pickup unit configured to receive wireless power from a wirelesspower transmitter by using magnetic coupling between the wireless powertransmitter and the wireless power receiver; and a communication/controlunit configured to control the wireless power and to performtransmission or reception of data based on communication with thewireless power transmitter, wherein the communication/control unitfurther configured to: transmit, to the wireless power transmitter, areceived power packet (RPP) which indicates a value of the wirelesspower received by the wireless power receiver, receive a bit patternfrom the wireless power transmitter in response to the RPP, the bitpattern being used for the wireless power transmitter to requestcommunication initiated by the wireless power transmitter, transmit, tothe wireless power transmitter, a response packet to allow thecommunication initiated by the wireless power transmitter, receive, fromthe wireless power transmitter, information indicating the target powerlevel in response to the response packet, adjust a guaranteed powerlevel adjusted by the wireless power receiver such that the target powerlevel is kept equal to or larger than the guaranteed power level,negotiate the guaranteed power level with the wireless powertransmitter.
 12. The wireless power receiver of claim 11, wherein thetarget power level is kept equal to or lower than a potential powerlevel which is the highest power provided by the wireless powertransmitter.
 13. The wireless power receiver of claim 11, wherein theguaranteed power level is adjusted by the wireless power receiver basedon the target power level.
 14. The wireless power receiver of claim 11,wherein the information indicating the target power level is 6 bits. 15.A method of data reception performed by a wireless power receiver, themethod comprising: receiving wireless power from a wireless powertransmitter by using magnetic coupling between the wireless powertransmitter and the wireless power receiver; transmitting, to thewireless power transmitter, a received power packet (RPP) whichindicates a value of the wireless power received by the wireless powerreceiver; receiving a bit pattern from the wireless power transmitter inresponse to the RPP, the bit pattern being used for the wireless powertransmitter to request communication initiated by the wireless powertransmitter; transmitting, to the wireless power transmitter, a responsepacket to allow the communication initiated by the wireless powertransmitter; receiving, from the wireless power transmitter, informationindicating the target power level in response to the response packet;adjusting a guaranteed power level adjusted by the wireless powerreceiver such that the target power level is kept equal to or largerthan the guaranteed power level; and negotiating the guaranteed powerlevel with the wireless power transmitter.
 16. The method of claim 15,wherein the target power level is kept equal to or lower than apotential power level which is the highest power provided by thewireless power transmitter.
 17. The method of claim 15, wherein theguaranteed power level is adjusted by the wireless power receiver basedon the target power level.
 18. The method of claim 15, wherein theinformation indicating the target power level is 6 bits.